Latin for “toxic” or “poison” A virus is a non-living microscopic particle, much smaller than a bacteria, which cannot grow or reproduce apart from a living cell. A virus invades living cells, called a host cell, and must use the host cell in order to replicate itself.

Viruses are not affected by antibiotics. Viruses contain genetic information, either DNA or RNA surrounded by a protein. Viruses are much smaller than a bacteria. Viruses must have a host cell in order to replicate. All viruses are harmful, where as some bacteria can be beneficial to organisms.

Most viruses have NO cure (Influenza, & HIV), but some viruses like Small- pox have vaccines. Vaccines contain a weakened or killed virus that provides immunity to the disease.

Viruses are NOT cells and are not made-up of cells. They don’t… Contain a nucleus or cytoplasm Eat Grow Carry on respiration Or perform other biological functions

A virus is surrounded by a capsid (protein coat) which determines the shape of the virus. The capsid contains nucleic acids (either DNA or RNA). Tail fibers for attachment to host cell.

DiseaseTransmissionSymptoms AIDS/HIVSexual contact; contaminated blood or needles Immune system failure; fatal Common Cold Inhalation, direct contact Sinus congestion, muscle aches, cough, fever SmallpoxInhalationBlisters, lesions, fever, blindness, scars; often fatal Influenza (Flu) InhalationHeadache, muscle ache, sore throat, cough, fatigue, fever, chills WartsDirect contactLumps on skin or mucus membranes

Virus Cycle Lytic and Lysogenic Cycles